The utility of hepatic artery velocity in diagnosing patients with acute cholecystitis

Ultrasound of the gallbladder: not the same bag of tricks

Imaging evaluation of the gallbladder is a fundamental skill in the majority of radiology practice. Due to ease of accessibility, low cost, lack of ionizing radiation, and excellent spatial resolution, ultrasound is often the first imaging modality used to evaluate the gallbladder. In this invited article we review and update how ultrasound can evaluate common pathologies including gallbladder polyps, tumefactive sludge, adenomyomatosis, and acute cholecystitis. We also discuss the role of Doppler, microvascular flow imaging, and contrast enhanced ultrasound in the sonographic assessment of the gallbladder.

A meta-analysis of the performance of ultrasound, hepatobiliary scintigraphy, CT and MRI in the diagnosis of acute cholecystitis

PURPOSE

To evaluate the recently reported relative diagnostic accuracy of US, CT, MRI, and cholescintigraphy for diagnosing acute cholecystitis.

METHODS

2 radiologists independently performed systematic electronic searches for articles published between 2000 and 2021 and applied inclusion/exclusion criteria. 2 different radiologists extracted data from the articles and scored each with a methodological quality tool. Pooled estimates of sensitivity and specificity were calculated with a bivariate linear mixed model. A second analysis made head-to-head comparisons (US vs. CT, US vs. cholescintigraphy). Factors were also analyzed for potential confounding effects on diagnostic accuracy.

RESULTS

Of 6121 initial titles, 22 were included. The prevalence of cholecystitis varied widely across studies (9.4-98%). Pooled sensitivity and specificity estimates were 69% (confidence limit [CL] 62-76%) and 79% (CL 71-86%) for US, 91% (CL 86-94%) and 63% (CL 51-74%) for cholescintigraphy, 78% (CL 69-84%) and 81% (CL 71-88%) for CT, and 91% (CL 78-97%) and 93% (CL 70-99%) for MRI. Regarding head-to-head comparisons, the sensitivity of CT (87.6%, CL 70-96%) was significantly higher than US (66.8%, CL 43-84%), while specificities (81.7% with CL 54-95% for US, 91.9% with CL 67-99% for CT) were similar. The sensitivity of cholescintigraphy (87.4%, CL 76-94%) was significantly greater than US (61.6%, CL 44-77%), while the specificity of US (82%, CL 65-92%) was significantly higher than cholescintigraphy (68%, CL 47-84%).

CONCLUSION

Recent data suggests that CT may have a higher sensitivity than US for diagnosing acute cholecystitis, with similar specificity. Cholescintigraphy remains a highly sensitive modality with lower specificity than previously reported. MRI remains under studied, but with promising results.

Sonographic Assessment of Acute Versus Chronic Cholecystitis: An Ultrasound Probability Stratification Model

OBJECTIVES

What sonographic variables are most predictive for acute cholecystitis? What variables differentiate acute and chronic cholecystitis?

METHODS

The surgical pathology database was reviewed to identify adult patients who underwent cholecystectomy for cholecystitis and had a preceding ultrasound of the right upper quadrant within 7 days. A total of 236 patients were included in the study. A comprehensive imaging review was performed to assess for gallstones, gallbladder wall thickening, gallbladder distension, pericholecystic fluid, gallstone mobility, the sonographic Murphy's sign, mural hyperemia, and the common hepatic artery peak systolic velocity.

RESULTS

Of 236 patients with a cholecystectomy, 119 had acute cholecystitis and 117 had chronic cholecystitis on surgical pathology. Statistical models were created for prediction. The simple model consists of three sonographic variables and has a sensitivity of 60% and specificity of 83% in predicting acute versus chronic cholecystitis. The most predictive variables for acute cholecystitis were elevated common hepatic artery peak systolic velocity, gallbladder distension, and gallbladder mural abnormalities. If a patient had all three of these findings on their preoperative ultrasound, the patient had a 96% chance of having acute cholecystitis. Two of these variables gave a 73-93% chance of having acute cholecystitis. One of the three variables gave a 40-76% chance of having acute cholecystitis. If the patient had 0 of 3 of the predictor variables, there was a 29% chance of having acute cholecystitis.

CONCLUSIONS

Gallbladder distension, gallbladder mural abnormalities, and elevated common hepatic artery peak systolic velocity are the most important sonographic variables in predicting acute versus chronic cholecystitis.

Performance of an algorithm for diagnosing acute cholecystitis using clinical and sonographic parameters

PURPOSE

Identify an algorithm using clinical and ultrasound (US) parameters with high diagnostic performance for acute cholecystitis.

METHODS

Consecutive emergency department (ED) patients from 4/1/2019 to 12/31/2019 were retrospectively reviewed to record non-US parameters and make US observations. Outcomes were categorized as either: (1) acute cholecystitis; or (2) negative acute cholecystitis. Pivot tables identified parameter combinations either not found with acute cholecystitis or with predictive value for acute cholecystitis to establish the algorithm. US Division radiologists finalized an US report prior to ED disposition without use of the algorithm. Radiologist impression and algorithm prediction for acute cholecystitis were categorized as either (1) acute cholecystitis; (2) negative acute cholecystitis; or (3) inconclusive.

RESULTS

Three hundred and sixty-six studies on 357 patients (mean age, 51 yrs ± 20 yrs; 215 women) met the inclusion criteria. 10.9% (40/366) of US studies had acute cholecystitis, 12.6% (46/366) had pathologically identified chronic cholecystitis without acute cholecystitis, and 76.5% (280/366) were negative acute cholecystitis. Algorithm compared to radiologist diagnostic performance was as follows: (1) sensitivity: 90.0% vs. 55.0%, p < 0.001; (2) augmented sensitivity (defined as when inconclusive categorization is considered consistent with acute cholecystitis): 100% vs. 85.0%, p < 0.001; (3) specificity: 93.6% vs. 94.8%, p = 0.50; (4) diagnostic rate (opposite of inconclusive rate): 96.4% vs. 93.2%, p = 0.04; (5) adverse outcome rate: 0.0% vs. 1.6%, p undefined.

CONCLUSION

For acute cholecystitis, an algorithm using non-binary ultrasound and clinical assessments had higher sensitivity, higher diagnostic rate, and fewer adverse outcomes, than subspecialty radiologist impressions.

Markedly elevated hepatic arterial velocity-HAV greater than 200 cm/s-is not specific to hepatobiliary disease

OBJECTIVE

The aim of the study was to review the different etiologies and outcomes of patients with hepatic artery velocities greater than 200 cm/s.

METHODS

This retrospective study included 88 hospitalized patients in whom angle-corrected proper hepatic artery flow velocities greater than 200 cm/s were obtained during an abdominal ultrasonographic examination. Peak systolic hepatic artery flow velocities, hepatic artery resistance index, and portal vein flow velocities were evaluated. The patients were then allocated to one of four groups based on their primary underlying diagnosis: structural liver disease, nonstructural liver disease, generalized infection, or miscellaneous.

RESULTS

The median hepatic artery velocity was similar for all groups, ranging from 226 to 238 cm/s. The maximum portal venous velocities were not significantly different between groups. No lab values were statistically different between the groups, except total bilirubin that was greater in the nonstructural liver disease group (8 mg/dL). Overall, 9/88 (10.2%) of patients with elevated hepatic artery velocity died within 30 days of their ultrasonographic examination.

CONCLUSION

Elevated hepatic artery velocity greater than 200 cm/s in hospitalized patients is not specific to primary hepatobiliary disease but may indicate acute hepatic dysfunction from other causes such as infection or sepsis.

Does measurement of the hepatic artery velocity improve the sonographic diagnosis of cholangitis?

OBJECTIVE

To determine the frequency of elevated peak systolic proper hepatic artery velocity (HAV) in patients with acute cholangitis and to determine the diagnostic performance of this metric relative to existing criteria.

METHODS

Between 9/2016 and 11/2017, 107 patients clinically suspected to have cholangitis were referred for an abdominal ultrasound. Of these, 56 patients had HAV measurements and were included in the final analysis. Clinical and imaging features, including HAV, HAV resistive index (RI), portal vein velocity (PVV), biliary dilation, and presence of an obstructive etiology were extracted. The diagnostic performance of HAV was compared to the existing available clinical criteria (Charcot's triad and 2018 Tokyo Guidelines). Elevated HAV was defined as HAV > 100 cm/s. Presence of cholangitis was determined by the discharge summary following medical workup and admission or observation.

RESULTS

32% had cholangitis while 68% did not. Average HAV for patients with cholangitis was 152 ± 54 cm/s versus 91 ± 44 cm/s for those without (p < 0.0001; t test). The HAV was elevated in 83% of patients with cholangitis. When considered in isolation, an elevated HAV had a high negative predictive value (90%), was more accurate (77%; 95% confidence interval 64-87%) than Charcot's triad (73%; 60-83%), and had similar accuracy compared to 2018 Tokyo Guidelines (79%; 66-88%). Substitution of conventional imaging criteria with elevated HAV in the 2018 Tokyo Guidelines yielded the highest overall accuracy of 84% (72-92%).

CONCLUSION

HAV is elevated in the majority of patients with cholangitis. Substitution of an elevated HAV for conventional sonographic criteria is more accurate than existing clinical criteria in identifying patients with cholangitis.

[Acute abdomen - gastrointestinal causes]

CLINICAL/METHODICAL ISSUE

Diagnostic imaging plays a crucial role in the assessment and stratification of pathologic conditions causing acute abdomen. This report provides information on etiology, clinical manifestations and therapeutic options for six common diseases resulting in acute abdomen-appendicitis, cholecystitis, bowel obstruction, diverticulitis, acute pancreatitis, and viscus perforation.

PERFORMANCE

Besides initial ultrasound, CT scans often represent the imaging gold standard for the diagnostic evaluation of acute abdomen.

PRACTICAL RECOMMENDATIONS

Depending on the underlying pathologic condition, sonography or CT is suitable for the stratification of the gastrointestinal disease causing acute abdomen.